For a long time, pressure sensitive adhesives have been used for attaching medical devices, such as ostomy appliances, dressings (including wound dressings), wound drainage bandages, devices for collecting urine, orthoses and prostheses to the skin.
Hydrocolloid adhesives containing hydrophilic particles or absorbents, which absorb moisture into the adhesive bulk and transmit moisture when conditions are saturated, are one well-known group of pressure sensitive adhesives useful for attaching medical devices to the skin. However, the retention of moisture in hydrocolloid adhesives may cause changes in the adhesive, such as swelling, loss of cohesion and disintegration. Non-absorbing adhesives on the other hand, may trap excessive moisture between the skin and adhesive, causing weakening of adhesion and maceration of the skin.
When hydrocolloid particles are incorporated into adhesives, the properties of the resulting adhesives change. Typically, the hardness of the adhesive will increase with the addition of hydrocolloid. This is often undesired in medical devices as it is preferred to have soft and skin-friendly adhesives being capable of following the movements of the skin. Furthermore, it is a disadvantage that the processing of the adhesive will be more difficult when working with hydrocolloid containing adhesives. Due to the increased hardness of the adhesive, the tackiness of the adhesive matrix decrease and may, prior to addition of hydrocolloids, need to be increased by increasing the adhesiveness of the composition, enhancing the risk of damaging the skin when the device is removed.
Due to the delicate nature of skin, there is a narrow window where a pressure sensitive adhesive can function as a good and skin friendly adhesive: On one hand, the adhesive should be able to attach the medical device to the skin and the device should not fall off during wear and, on the other hand, removal of the medical device from the skin should not cause damage to the skin.
It has now surprisingly been found that a pressure sensitive adhesive composition can be made that is useful in medical devices, which can be removed without pain. Furthermore, the adhesive composition of the invention maintain the absorbing characteristic, while being applied in a thin layer.